Underwater pipe positioning apparatus

ABSTRACT

In lowering a pipe string assembly from an above water drilling rig or platform into a subbottom well bore, a destructible positioning and protecting device is affixed to the lower end of the pipe string assembly. Such positioning and protecting device comprises a protective closure member for closing the lower end of the pipe string assembly. A fluid passageway system is formed within the body of the closure member for enabling fluid to be pumped down the pipe string assembly and emitted from the closure member in a lateral direction relative to the pipe string assembly for causing lateral movement of the lower end thereof, whereby such lower end may be brought into alignment with the mouth of the well bore. In some embodiments, a signal radiating device is carried within and protected by the closure member for use in ascertaining the position of the lower end of the pipe string assembly relative to the mouth of the well bore.

United States Patent Rosser et a].

[54] UNDERWATER PIPE POSITIONING APPARATUS [72] Inventors: Eugene P. Rosser; Howard L Lorenz, both of Houston, Tex.

Noble Drilling Corporation, Tulsa, Okla. by said Rosser 221 Filed: May 11,1970

21 Appl. No.: 36,231

[73] Assignee:

[ 151 3,664,442 1 May 23,1972

3,368,619 2/1968 Postlewaite l66/.6

Primary Examiner-James A. Leppink Attorney-Jack W. Hayden [57] ABSTRACT In lowering a pipe string assembly from an above water drilling rig or platform into a subbottom well bore, a destructible positioning and protecting device is affixed to the lower end of the pipe string assembly. Such positioning and protecting device comprises a protective closure member for closing the lower end of the pipe string assembly. A fluid passageway system is formed within the body of the closure member for enabling fluid to be pumped down the pipe string assembly and emitted from the closure member in a lateral direction relative to the pipe string assembly for causing lateral movement of the lower end thereof, whereby such lower end may be brought into alignment with the mouth of the well bore. In some embodiments, a signal radiating device is carried within and protected by the closure member for use in ascertaining the position of the lower end of the pipe string assembly relative to the mouth of the well bore.

13 Claims, 6 Drawing Figures PATENTEDMAY 23 I972 3, 66-4, 442

sum 2 or 3 60 5/ BY &

Richard Bea /ITTORNEYS UNDERWATER PIPE POSITIONING APPARATUS CROSS-REFERENCE TO RELATED APPLICATION The present application relates to another embodiment of the invention of our application Ser. No. 832,673, filed June 12, 1969 for Devices and Methods for Protecting and Guiding Rock Bits," now abandoned, and Ser. No. 107,786, filed Jan. 19, 1971 for Methods and Arrangement for Protecting and Guiding Drilling Bits.

BACKGROUND OF THE INVENTION This invention relates to methods and apparatus for guiding a column or string of pipe from an above water location to a desired underwater location.

There are various occasions when it is desired to drill a well bore into the subbottom soil material and earth formations underlying a body of water. Such body of water may be part of an ocean, a sea, a gulf, a bay, a lake, a river, or the like and may be as much as several thousand feet deep at the location of the well bore. Such underwater well bores or boreholes are drilled for various purposes, such as, for example, the recovery of oil and gas and various types of minerals from the subbottom earth formations, the obtaining of various geological data and the like. Such underwater well bores are commonly drilled by means of equipment located aboard a drilling barge or drilling platform or other above water structure or floating vessel.

There are various occasions during the drilling of underwater boreholes and, for the case of oil and gas wells, during the subsequent production and maintenance operations conducted therein when it becomes necessary to lower a string of pipe from a drilling platform or drilling barge or other above water structure or vessel down through the water and into the previously drilled portion of the subbottom borehole. One example is the case where, during the drilling of the well bore, it becomes necessary to pull the drill string out of the hole and back aboard the drilling platform or vessel for purposes of changing the drill bit. Thereafter, the drill string is lowered back through the water and into the subbottom well bore for purposes of continuing the drilling operation. Another example occurs for the case of an oil or gas well where, after the completion of the drilling phase, it is necessary to lower casing pipe into the well bore for purposes of completing the well and making it ready for production.

This pipe lowering operation is not an easy task. Consider, for example, the case where a string of pipe is to be lowered from a floating vessel, down through several hundred feet of water and into ,the mouth of a subbottom well bore on the order of eight inches in diameter. As is apparent, there is a problem in getting the bottom end of the pipe string or drill string to hit the mouth of the well bore. The problem is somewhat akin to threading a needle, except that, in this case, the operator doing the aiming is located several hundred or several thousand feet away on the drilling platform or vessel. The problem is further complicated by the fact that a string of pipe having a length of several hundred or several thousand feet is a fairly flexible thing and is readily subject to being deflected bv underwater currents. In addition, the platform or ship at the surface is likely to be undergoing movement caused by wave action, wind and tides.

At the present time, there is no satisfactory means of directing the bottom end of a string of pipe to the mouth of a subbottom well bore, other than by moving the surface ship or platform and rotating the pipe in the hope that the pipe string and the mouth of the well bore will come into alignment with one another. Needless to say, such present method is dependent on the more or less random movements of the surface ship and the subsurface water currents. As a consequence, this process is very time consuming at best and may, in some cases, be impossible to accomplish.

SUMMARY OF THE INVENTION It is an object of the invention, therefore, to provide a method of lowering a pipe string assembly to a desired underwater location.

It is another object of the invention to provide a method of positioning the underwater end of a vertically extending pipe string assemblv so as to bring it into alignment with the mouth of a subbottom well bore.

It is a further object of the invention to provide an underwater pipe positioning device of relatively economical and inexpensive construction for bringing the lower end of a vertically extending pipe string into alignment with a desired point near the bottom of a relatively deep body of water.

It is an additional object of the invention to provide a positioning and protecting device for a drill bit mounted on the lower end of a string of drill pipe for enabling the drill bit to be brought into alignment with the mouth of an underwater well bore and for protecting the bit from damage during the lowering, positioning and entry operations and during its descent in the subbottom well bore.

It is a further object of the invention to provide an underwater pipe positioning and protecting device for positioning and protecting a drill bit mounted on the lower end of the pipe when same is lowered through a body of water into a subbottom well bore and wherein the positioning and protecting device may be readily removed from the bit whenever desired for purposes of placing the bit in condition to continue the drilling operation.

In accordance with one feature of the invention, a positioning and protecting device for enabling a pipe string assembly to be lowered to a desired underwater location comprises protective closure means for closing and protecting the lower end of the pipe string assembly. Such positioning and protecting device further includes fluid passage means carried by the closure means for emitting fluid laterally of the pipe string assembly for causing lateral movement of the lower end thereof.

In accordance with another feature of the invention, a method of directing the lower end of a downwardly extending pipe string assemblv to a desired underwater location is provided which includes the step of affixing protective closure means to the lower end of the pipe string assembly for closing and protecting such lower end, such closure means including fluid passage means for emitting fluid in a lateral direction relative to the pipe string assembly. The method also includes the step of lowering the pipe string assembly into the water. The method further includes sensing the position of the lower end of the pipe string assembly relative to the desired underwater location. The method additionallv includes the step of emitting fluid from the interior of the pipe string assembly by way of the fluid passage means for adjusting the position of the lower end of the pipe string assembly relative to the desired underwater location.

For a better understanding of the present invention together with other and further objects and features thereof, reference is had to the following description taken in connection with the accompanying drawings, the scope of the invention being pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS Referring to the drawings:

FIG. 1 is an elevational view showing in a diagrammatic manner the lowering of a pipe string assemblv from a floating drilling platform to an underwater well bore;

FIG. 2 is an enlarged cross-sectional view showing a first embodiment of a positioning and protecting device constructed in accordance with the present invention and affixed to the lower end of an open-ended string of well pipe;

FIG. 3 is an enlarged cross-sectional view showing a second embodiment of a positioning and protecting device constructed in accordance with the present invention and afiixed to a drill bit located at the lower end of a string of drill pipe;

FIG. 4 is an enlarged cross-sectional view showing third embodiment of a positioning and protecting device wherein a signaling device is carried within and protected by the positioning and protecting device for providing means for determining the position of the lower end of the pipe string assembly;

FIG. 5 is similar to FIG. 4 but shows a modified form of signaling device; and

FIG. 6 shows a further embodiment adapted for use with a diamond drill bit and including a facility for receiving a wireline scanning device for ascertaining the location of the drill bit with respect to the mouth of the underwater well bore.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Referring to FIG. 1, there is shown a representative situation wherein the present invention may be used. The situation shown in FIG. 1 is for purposes of illustration only and the use of the invention is not limited to this particular example. As shown in FIG. 1, a rotary drilling rig 10 is located on a floating vessel or drilling platform 11. Rotary drilling rig 10 is of the type commonly used in drilling oil and gas wells. A pipe string assembly 12 is suspended from the drilling platform 1 1 and extends downwardly through a body of water 13 to a point just above the mouth of a metal funnel device 14 located at and resting on the bottom 15 of such body of water 13. The funnel device 14 is located at the upper end or mouth of a subbottom well bore 16 which extends downwardly into the subbottom earth material. The funnel device 14 is placed in position on the bottom 14 before the drilling of the well bore 16 is initially commenced and thereafter serves to facilitate reentry into the well bore 16.

As can be appreciated, the depth and texture of the body of water 13 will frequently be such that the operating personnel on board the drilling platform 11 will not be able to visually observe the location of either the lower end of the pipe string assembly 12 or themouth of the well bore 16. In such cases, it is necessary to provide some means for ascertaining such locations so that the position of the pipe string assembly 12 can be altered, when necessary, to bring it into alignment with the well bore 16. Various methods of tracking the position of the lower end of the pipe string assembly 12 will be set forth in detail in connection with the descriptions of the various embodiments of the invention set forth hereinafter. One such tracking or locating method is illustrated in FIG. 1 by sets of sounding buoys 17a, 17b, and 170 anchored at different depths with respect to the bottom 15. This method will now be briefly considered in order to provide an initial understanding of the problem.

As indicated in FIG. 1, a first group of three sounding buoys 17a (only two of which are visible) is anchored at the bottom 15 of the body of water 13, the buoys 17a being at fixed and known lateral locations relative to the mouth of the well bore 16. Buoys 17a are deployed in a triangular pattern. The other sets of buoys 17b and 170 are similarly deployed, except that buoys 17b are anchored at an intermediate depth and the buoys 17c are anchored at the surface of the water 13. The number of sets of buoys used will depend on the depth of the water and the other operating conditions being encountered. In many cases, a single set will suffice.

Considering in detail the bottom anchored set 17a, each of the three buoys in the set or group 17a carries appropriate accoustical or sonic transmitting and receiving equipment for purposes of sensing and determining the distance between the buoy and the lower end of the pipe string assembly 12. An insulated electrical signaling cable (not shown) runs from each of the buoys 17a to the deck of the drilling platform 11. At periodic intervals, a sonic pulse is transmitted from one of the buoys 17a and travels upwardly through the body of water 13 and is partially reflected by the lower end of the pipe string assembly 12. The elapsed time from the emission of a sonic pulse by one of the buoys 17a the reception of the reflected sonic energy at this same one of the buoys 17a provides a measure of the distance between such buoy and the lower end of the pipe string assembly 12.

By using a group of three buoys 17a which take turns in transmitting sonic pulses and receiving the reflections from the lower end of the pipe string assembly 12, the position of the lower end of the pipe string assembly 12 relative to the mouth of the well bore 16 can be determined. The results of this triangulation process are displayed on a radar type cathode-ray oscilloscope display device located aboard the drilling platform 11. Such oscilloscope is located in convenient view of the person in charge of the pipe lowering operation. By looking at such oscilloscope display, such person can see at a glance the position of the lower end of the pipe string assembly 12 relative to the mouth of the well bore 16.

Where used, the other groups of buoys 17b and 170 are constructed and operated in a similar manner. Where more than one set of buoys is employed, they may be operated during different stages of the lowering of the pipe string assembly 12, the particular group being operated at any given moment depending on the depth of the lower end of the pipe string as sembly 12 at such moment.

The distance from the surface of the water 13 to the bottom 15 may be anywhere from feet up to several thousand or more feet. Thus, in general, a fairly considerable length of pipe will be suspended from the drilling platform 1 1. As a consequence, there will be a considerable tendency for such pipe to bend and sway and swing back and forth as it is lowered through the water 13 toward the mouth of the well bore 16. Such swinging and swaying may be caused in whole or in part by underwater currents. It may also be caused to a greater or lesser extent by the movements of the drilling platform 11 where such platform 11 is of the floating type. In any event, it is not an uncommon occurrence to find that the lower end of the pipe string assembly 12 is not in alignment with the top opening in the funnel device 14 as the lower end of such pipe string assembly 12 nears the bottom 15. An example of a displaced position for the lower end of the pipe string assembly 12 is indicated in dotted line form at 12.

In accordance with the means available heretofore, the pipe string assembly 12 would be lowered to a depth a few feet above the top level of the funnel device 14, at which point the lowering would be discontinued. The pipe is then allowed to move about on its own until such time as the lower end thereof should eventually cross over the opening in the top of the funnel device 14. When it does eventually pass over such opening, then the pipe string assembly 12 is lowered the remaining distance into the funnel device 14 and, thereafter, into the subsurface well bore 16.

The only control the operator aboard the drilling platform has over the situation is the movement of the lower end that can be obtained by maneuvering the drilling platform 11 and by rotating the pipe string assembly 12. Unfortunately, where the pipe string assembly 12 is relatively long, this does not give very much control. Consequently, the accomplishment of the alignment is usually very time consuming and sometimes impossible.

In accordance with the present invention, the time consuming waiting period of the foregoing process is substantially reduced by further including at the lower end of the pipe string assembly 12 a positioning and protecting device 18 for enabling the operator aboard the drilling platform 11 to have a positive and selective control over the movement of the lower end of the pipe string assembly 12. In particular, a positioning and protecting device 18 is provided at the lower end of the pipe string assembly 12 for emitting a jet of fluid in a lateral direction relative to the pipe string assembly 12 whenever the operator aboard the drilling platform 11 desires that such jet of fluid should be emitted. For the example indicated in outline form in FIG. 1, the jet of fluid is indicated at 19. The emission of such a fluid jet in one direction serves to produce a thrust on the lower end of the pipe string assembly 12 in the opposite direction. This thrust moves the lower end of the pipe string assembly from the outline position 12 to the position shown in solid line form, the latter being the desired position for entry into the funnel device 14.

The emission of the fluid jet 19 is produced by pumping fluid down the interior of the pipe string assembly 12. This may be accomplished, for example, by means of the drilling fluid pump located aboard the drilling platform 11. Such pump is connected to the top end of the pipe string 12 and is turned on to cause the emission of the fluid jet 19 and is turned off to discontinue the emission of the fluid jet 19. Aiming of the fluid jet 19 in the proper compass direction is accomplished by rotating the pipe string assembly 12 by means of the rotary table or other apparatus located aboard the drilling platform 11. The progress of the positioning operation is followed by means of the radar type oscilloscope display located aboard the drilling platfonn 11. As a consequence, with the present invention, the lower end of the pipe string assembly 12 can be brought into alignment with the top opening in the funnel device 14 in fairly short order.

Among other things, the manner of construction of the positioning and protecting device 18 will depend upon the particular type of pipe making up the pipe string assembly 12 and on the type and nature of any device or tool that may be connected to the bottom end of the pipe string assembly. For example, the pipe string assembly 12 may be formed of lengths of drill pipe, casing pipe, riser pipe, production tubing, or any other type of pipe that might be used in connection with a well bore. In the case of drill pipe, for example, a drill bit will be connected to the lower end of the pipe string. Such bit may be a conventional rock bit, a diamond drill bit, or a diamond core bit.

Referring now to FIG. 2, there will be described a manner of construction for a positioning or protecting device for the case. where the pipe string assembly 12 is made up of a string of pipe which is open ended at the lower end and which is to be set into the well bore 16 for purposes of completing the well. The positioning and protecting device is indicated generally at 20. Such device 20 is mounted on the lower end of a pipe string assembly 21. The positioning device 20 includes a closure member 22 for closing the lower end of the pipe string 21 and a coupling member 23 for connecting the closure member 22 to the threaded portion at the bottom end of the pipe string 21. As such, the coupling member 23 may take the form of an internally threaded pipe collar.

The positioning device 20 further includes fluid passage means formed in the closure member 22, which passage means includes first fluid conduits 24b and second fluid conduit 24e within the body of the closure member 22.

The first fluid conduits 24b and second fluid conduit 24e provide an arrangement for conducting fluid from the interior of the pipe string assembly 21 to be discharged laterally thereby causing lateral movement of the lower end of the pipe string assemblv 21. The details of one arrangement suitable to accomplish the functions and objects of the invention will be described.

The first fluid conduits 24b of the passage means provide ports 240 at one end of the passage means which communicate with the interior of the pipe string assembly 21 as shown in FIG. 2. The second fluid conduit 24e of the passage means provides a port 24g at the other end of the passage means which is located laterally of the longitudinal axis of the pipe string assemblv 21, and to accomplish this, the portion of the fluid conduit 24e immediately adjacent the port 24g is shown as extending in a lateral direction relative to the pipe string assembly 21. The port 24g communicates with the exterior environment surrounding the closure member 22 and it along with the portion of fluid conduit 24e which extends laterally provide an arrangement designated generally at 24 for emitting fluid laterally of the pipe string assembly 21 for causing lateral movement of the lower end thereof.

Fluid pressure responsive means is formed in the closure member 22 between one end of the fluid passage means as represented by ports 24c and the other end of the fluid passage means as represented by the port 24g. The function of pressure responsive means will be described in greater detail and is illustrated as including a laterally extending cavity 24a formed within the body of closure member 22 and which intersects the fluid passage means between ports 240 at one of its ends and port 24g at its other end. Each of the first fluid conduits 24b formed within the body of the closure-member 22 extends from the cavity 24a to the interior of the pipe string assembly 21, provides, as noted, ports 24c communicating with the interior of the pipe string assembly 21 and second ports 24d communicating with the interior of the cavity 24a.

Fluid conduit 24e formed within the body of the closure member 22 extends from the cavity 24a to the exterior surface of the closure member 22 on one side thereof, as previously described and includes a port 24f communicating with the interior of the cavity 24a and the port'24g.

In use, the positioning device 20 is connected to the lower end of the pipe string 21 and such pipe string is then lowered through the body of water 13 to a depth a few feet above the top level of the funnel device 14. The position of the lower end of the pipe string 21 is observed by means of the sounding buoys 17a, 17b, and 17c and the cathode-ray tube display previously considered, the latter being located on the drilling platform 11. If the lower end of pipe string 21 is not in alignment with the funnel device 14, then fluid is pumped down the interior of the pipe string 21 to cause the emission of a laterally directed fluid jet from the lateral outlet port 24g. This produces a lateral movement of the lower end of the pipe string 21. The pipe string 21 is rotated or turned the appropriate amount so that the fluid jet will move the lower end of the pipe string 21 into alignment with the opening in the top of the funnel device 14, whereupon the emission of the fluid jet is discontinued. The pipe string is then lowered into the funnel device 14 and into the well bore 16 located therebelow. The pump pressure may be varied as is necessary to obtain a desired rate of lateral movement for the pipe string 21 such that the lower end thereof may be brought to rest above the funnel device 14.

The purpose of the laterally extending cavity 24a is to enable the closure member 22 to be at least partially dislodged from the pipe string assembly 21 after such assembly has entered the subbottom well bore 16 and the positioning capability is no longer needed. In other words, the closure member 22 is of a destructible nature such that it can be removed from the pipe string assembly 21 at the appropriate time. This is accomplished by pumping fluid down the pipe string assembl 21 and increasing the pressure of such fluid until the resulting hydraulic action within the cavity 24a causes the portion of the closure member 22 below such cavity to break awav from the remainder of the closure member 22 below such cavity to break awav from the remainder of the closure member 22. This fracturing process will also normally break awav the center portion of the closure member 22 located above the cavity 24a. The hydraulic pressure used to break up the closure member 22 is, of course, substantially greater than the hydraulic pressure which is used when it is desired to emit a fluid jet from the port 24g for positioning purposes.

'To facilitate the breaking up of the closure member 22, such member is formed of a relatively frangible material. In the illustrated embodiment, this material is indicated as being a granular cementitious material composed of, for example, a mixture of cement plus a suitable aggregate, such as sand. While a granular cementitious material offers certain advantages, it should be noted that other types of materials may instead be used. For example, the closure member 22 may instead be formed of a plastic material such as, for example, epoxy resin, polyvinyl chloride, or the like.

The closure member 22 may be formed by means of a molding process wherein the coupling member 23 is positioned in an appropriate molding form and the material to form the body of the closure member 22 is thereafter poured into such molding form and allowed to harden. In such case, the various portions of the fluid passage means 24 may be formed by locating a removable molding core structure of the same shape as the passage means 24 in the molding form before the pouring of the molding material. In order to enable removal of the passage forming core structure after the molding material has hardened, such core structure can be made of a material which may be subsequently dissolved or flushed from the passage means 24. As such, the passage forming core structure may be made of, for example, paraffin or other relatively rigid wax-like material which can thereafter be melted and caused the flow out of the passage means 24 by heating same.

The foregoing method of fabricating the closure member 22 is intended by way of example only. Our copending application hereinbefore referred to discloses a method of fabrication which can be employed to form the closure means 22 of the present invention.

Referring now to FIG. 3, there is shown the case where the pipe string assembly 12 is comprised of a string of drill pipe 30 having a roller cone type drill bit 31 connected to the lower .end thereof. Considering briefly the drill bit 31, it includes a set of intermeshing roller cones 32 which are rotatably mounted on downwardly extending leg or shank portions of the bit 31. Located within the interior of the drill bit 31 is a system of fluid passageways 33 which communicate with the interior of the drill pipe 30 and which extend to and terminate at a series of jet nozzles 34, which nozzles point downwardly in the general direction of the roller cones 32. Such jet nozzles 34 emit drilling fluid during the drilling process for purposes of cleaning the roller cones 32 and aiding in the removal of drill cuttings from the bottom of the well bore.

There is further shown in FIG. 3 a positioning and protecting device 40 which includes a closure member 41 which is fitted over and encloses the roller cone portion of the drill bit 31. The closure member 41 includes a nose portion 41a which extends longitudinally a short distance, on the order of a few inches, below the lower extremities of the roller cones 32. The closure member 41 further includes leg portions 41b which extend upwardly between the shanks of the drill bit 31 and provide a seal with the edges of such shanks and the extremities of the upper body portion and the nozzle rib portions of the drill bit 31. The exterior of the closure member 41 is shaped to provide longitudinal recesses 410 which enable well fluid to move past the closure member 41 when such member is lowered into the well bore 16. Thus, the side contour of the closure member 41 corresponds approximately to the contour of the underlying portion of the drill bit 31. The closure member 41 encloses the lower portion of the drill bit 31 so as to prevent fluid from leaving the drill bit 31 other than in the manner set forth hereinafter.

The positioning and protecting device 40 also includes fluid passage means, indicated generally at 42 which includes a series of fluid conduits 42b formed within the body of the closure member 41, and fluid conduits 42c formed in the body of the closure member 41. The passage means 42 includes a set of laterally extending cavities 42a individually located adjacent and partially in contact with different ones of the roller cones 32. The conduits 42b individually extend from different ones of the jet nozzles 34 of the drill bit 31 to different ones of the cavities 42a. This establishes fluid communication between the jet nozzles 34 and the cavities 42a. The fluid conduits 42c extend from different ones of the cavities 42a to a common outlet conduit or passage 42d having a port 42e located on one of the longitudinally extending sides of the closure member 41. These conduits 42c and the common conduit 42d provide fluid communication between the cavities 42a and the external environment outside of the closure member 41.

As in the earlier embodiment, the closure member 41 is of a destructible nature and, as such, is made of a relatively frangible material for enabling its destruction or removal at a desired time. The closure member 41 may be formed of, for example, a granular cementitious material, such as a mixture of cement and aggregate. Such material is mixed with water to form a slurry which is thereafter molded around the roller cone portion of the drill bit 31 and allowed to harden. This molding process may be accomplished in the manner set forth in greater detail in applicants copending US. Pat. application Ser. No. 832,673, filed June 12, 1969, and entitled Devices and Methods for Protecting and Guiding Rock Bits." The devices described in this copending application are of a somewhat different form of construction, but the general techniques set forth for fabricating such devices are also applicable to the present devices.

As indicated in such copending application, the cavity forming pieces for cavities 42a may be composed of paraffin or other wax-like material, while the conduit forming pieces for conduits 42b, 42c, and 42d may be short lengths of plastic tubing. The drill bit 31 is placed in a molding form in an upside down manner and the cavity and conduit forming pieces are set in place on the drill bit. Also, a sand core 43 is located intermediate the roller cones 32 in the region adjacent the main body of the drill bit 31. Thereafter, the cement slurry or other molding material is poured into the molding form and allowed to harden. After that, the combined unit formed by the drill bit 31 and the positioning and protecting device 40 is removed from the molding form and the paraffin material is removed from the cavities 420.

In use, the positioning and protecting device 40 is operated in much the same manner as considered for the earlier embodiment. After lowering the drill string 30 through the body of water 13 to bring the drill bit 31 to a point near the bottom thereof, the drill bit 31 is brought into alignment with the top opening of the funnel device 14 by pumping fluid down the interior of the drill string 30 and out of the laterally directed outlet port 42c of the fluid passage means 42. After the drill bit 31 is lowered into the well bore 16 and it is desired to resume the drilling operation, drilling fluid is pumped down the drill string 30 and the pressure thereof is increased to the point where the hydraulic action in the cavities 420 causes the bottom portion of the closure member 41 to break free from the drill bit 31. This exposes the cutting teeth of the roller cones 32. Thereafter, the drill bit 31 is rotated and weight applied thereto in the normal manner to proceed with the drilling operation. Rotation of the roller cones 32 causes the remaining portion of the closure member 41 to break up and to be flushed out of the well bore along with the earth formation drill cuttings. The nose portion 41a which was previously broken off is chewed up in the drilling process and is also flushed out of the well bore.

In addition to emitting the lateral fluid jet which supplies the lateral thrust for positioning the lower end of the drill string assembly 30, the closure member 41 also serves the important function of protecting the drill bit 31 from damage during the reentry of the drill bit 31 into the well bore 16 and during the subsequent descent of the drill bit 31 to the bottom of such well bore 16. Thus, for example, should the drill bit 31 strike the funnel device 14 rather abruptly during the reentry, the closure member 41 would act to protect the roller cones 32 and prevent injury or damage thereto.

Referring now to FIG. 4, there is shown a somewhat different form of positioning and protecting device 50 for use on the drill bit 31. Except as hereinafter mentioned, the device 50 is of the same construction as the device 40 of FIG. 3. As in the previous embodiment, the positioning and protecting device 50 includes a closure member 51 for enclosing and protecting the roller cone portion of the bit 31. As a first point of difference, on the other hand, the device 50 includes a signal radiating mechanism represented by an acoustical or sonic impulse transmitter 52 for use in ascertaining the location of the drill bit 31 relative to the mouth of the well bore 16. This acoustic or sonic transmitter 52 is carried within and protected by the closure member 51 at a point below the lower end of the drill bit 31. The transmitter 52 is a self-contained unit having an internal sound generating mechanism for periodically or intermittently generating a burst of acoustical or sound wave energy which is radiated outwardly through the case of the transmitter unit 52 and the closure member 51 and into the surrounding body of water.

As before, the closure member 51 is provided with an internal fluid passage system 53 for emitting a lateral jet of fluid from a port 53a on one side of the closure member 51. The portion of this fluid passage system 53 below the laterally extending cavities 53b thereof is of a somewhat different form of construction. In particular, such lower portion includes a circular manifold passage 530 formed within the body of the closure member 51 at a point below the cavities 53b, such manifold passage 53c encircling the signal radiating device 52. Fluid conduits 53d extend from the manifold passage 53c to the cavities 53b and provide fluid communication therebetween. A further fluid conduit 53c runs from such manifold passage 530 to the side wall of the closure member 51, the mouth of such passage 53e forming the outlet port 53a.

Considering now the use of the positioning and protecting device 50 of FIG. 4, it will be assumed that such device 50 is used in the FIG. 1 environment and that the pipe string assembly 12 of FIG. 1 represents the string of drill pipe 30 of FIG. 4. It will be further assumed that the sounding buoys 17a, 17b, and 170 of FIG. 1 are not used and that, instead, a set of three hydrophone devices 11a are attached to the bottom of vessel 11, such hydrophone devices 11a being deployed in a triangular pattern. Before the drilling of the well bore 16 is commenced, the drilling vessel 11 is navigated to a location as near as possible above the desired location for the subbottom well bore. An intermittent-type sound wave transmitter unit is then dropped or lowered to the water bottom at a point as close as possible to the location desired for the well bore. Such transmitter location may correspond to, for example, the position represented by the left-hand one of the buoys 17a in FIG. 1. Such transmitter unit periodicallv emits a pulse or burst of acoustical energy which radiates upwardly through the water 13 and is detected by the hydrophone devices 11a.

By triangulation, the hydrophones 11a precisely determine the location of the vessel 11 with respect to the bottom located sonic transmitter unit, which unit is thereafter used as a bottom located reference point. By use of known naviga tional techniques, the geographical location of the drilling vessel- 11 can be accurately determined. Thus, knowing the geographical location of the vessel 11 and the location of such vessel relative to the bottom located reference point establishes the geographical location of such bottom located reference point. With the aid of this information, the vessel 11 is maintained at the proper location and the funnel device 14 is lowered to and set in place on the water bottom 15. This fixes the location of the funnel device 14 with respect to the bottom located sonic transmitter at the reference point.

Thereafter, the drill string 30 having the drill bit 31 and the positioning and protecting device 50' attached to the lower end thereof is lowered down through the water 13 until the positioning and protecting device 50 is a few feet above the top of the funnel device 14. The sonic transmitter 52 in the device 50 radiates periodic or intermittent bursts of sonic energy which are detected by the hydrophones 11a on the drilling vessel 11. By triangulation, this enables an accurate determination of the location of the positioning and protecting device 50 relative to the vessel 11. At the same time, the bottom located sonic transmitter at the reference point is continuing to emit intermittent bursts of sonic energy, such bursts having their own characteristic frequency, such frequency (or tone) being different from that of the sonic transmitter 52 to enable the signals from the two sources to be separately distinguished. Thus, the location of the vessel 11 relative to such reference point continues to be monitored. Since the location of such reference point relative to the funnel device 14 is known, this in turn provides a determination of the position of the positioning and protecting device 50 with respect to the funnel device 14. Preferably, the results of these determinations are monitored and displayed in a continuous manner on a cathode-ray tube display device aboard the drilling vessel 11 to provide a continuous picture of the locations of the funnel device 14 and the drill bit transmitter unit 52 relative to the vessel 11.

If the positioning and protecting device 50 at the lower end of the drill string 30 is not in alignment with the mouth of the funnel device 14, then fluid is pumped down the interior of the drill string 30 to cause the emission of a laterally directed fluid jet from the lateral outlet port 530. The resulting lateral movement of the lower end of the drill string 30 is then observed by means of the cathode-ray tube display. If such movement is in the wrong direction, then the drill string 30 is rotated or turned the appropriate amount to bring the direction of such movement to the desired direction. The emission of the fluid jet continues until the lower end of the drill string 30 is in alignment with the mouth of the funnel device 14, whereupon such emission is discontinued. The drill string 30 including the bit 31 and the device 50 is then lowered into the funnel device 14 for purposes of commencing the drilling of the well bore 16.

Prior to the commencement of drilling, the fluid pressure in the drill string 30 is increased to or above the point necessary to cause a breaking away of the portion of the positioning and protecting device 50 located below the laterally extending cavities 53b. The drilling of the well bore 16 is then commenced. Such drilling continues until the drill bit needs replacing or until some other event occurs which requires a return of the drill bit 31 to the drilling vessel 11. Before the drill string 30 is again returned to the well bore 16, a new drill bit 31 having a new positioning and protecting device 50 mounted on the end thereof is connected to the lower end of such drill string 30. Drill string 30 is then lowered back through the body of water 13 and is brought into alignment with the mouth of the funnel device 14 in the same manner-as previously considered. The drill string 30 is then run into the well bore 16, the positioning and protecting device removed, and the drilling of the well bore 16 resumed.

Referring now to FIG. 5, there is shown a modified form of the invention which is generally similar to the embodiment of FIG. 4 except that a somewhat different form of signaling device is employed. As indicated in FIG. 5, there is provided a positioning and protecting device 60 having a protective closure member 61 which is fitted over and encloses the roller cone portion of the drill bit 31, the construction being the same as in FIG. 4 except where otherwise noted. The signaling device of the FIG. 5 embodiment includes a transponder unit 62 carried within the nose portion of the closure member 6 l at a point below the lower end of the drill bit 31 and an energy source unit 63 carried within the lower end of the drill pipe 30 and resting on the top end of the bit stem. The transponder unit 62 includes a sonic receiver for detecting the arrival of sonic interrogation pulses and a sonic transmitter connected thereto for transmitting a sonic echo pulse or reply pulse following detection of a received interrogation pulse. The energv source unit 63 includes electrical batteries or fuel cells or the like for supplying the operating energv to the circuits and devices in the transponder unit 62.

Energy source 63 is connected to transponder 62 by way of leads 64 which are connected to the source 63 by way of a removable plug 65 and to the transponder 62 by way of a second plug 66. Leads 64 extend downwardly through bit passage 33, jet nozzle 34, and a fluid conduit 67 formed within the body of the closure member 61. The lower portion of leads 64 is embedded in the nose portion of the closure member 61, the same as is the transponder unit 62. The energy source unit 63 is maintained in an off center position in the drill string 30 by means of flexible spring arms 68. A retrieving hook 69 is mounted on top of the energy source 63 for enabling later removal of the energy source 63 by means of a wireline retrieving tool lowered down within the drill string 30. If desired, of course, the energy source 63 could instead be provided with centering arms for mounting same in the center of the drill pipe 30, leaving sufficient clearance around the sides thereof to permit circulation of fluid therepast.

The fluid passage system for providing the lateral thrust, which system is generally indicated at 70, is generally the same as the corresponding fluid passage system in FIG. 4 except that, in the FIG. 5 case, a single laterally extending cavity 700 is provided, such cavitv being provided with a greater lateral dimension so as to include the regions formerly occupied by the individual cavities in the earlier embodiment.

In use, the positioning and protecting device 60 is used in much the same manner as that previously considered for the corresponding device 50 in FIG. 4 except that, in the FIG. 5 case, the transponder unit 62 must receive an interrogating pulse before it will emit a reply pulse. For this reason, there is further mounted on the bottom of the drilling vessel 11 or on some suitable sounding buov located, for example, at the surface of the water 13, a sonic transmitter unit which may be turned on to emit and radiate intermittent interrogating pulses. Also, for sake of a different example, it will be assumed in this embodiment that the reference signaling device initially placed on the water bottom 15 near the funnel device 14 is also a transponder type unit having both a sonic pulse receiver and a sonic pulse transmitter. This device is constructed to detect bursts of sonic energy having a different frequency or tone than the transponder unit 62 in the positioning and protecting device 60 so that the two may be operated separately from one another and without interfering with one another. This will require the use of a second sonic pulse transmitter on the drilling vessel 11 or the surface of the water 13 for transmitting the interrogating pulses of different frequency to the reference point transponder.

When it is desired to lower a new drill bit into the well bore 16, the surface located interrogating pulse transmitter units are turned on for purposes of intermittently interrogating the subsurface transponder units for purposes of causing same to emit their characteristic echo pulses which are detected by the hydrophones 11a from whence their relative positions are determined by means of the previously considered triangulation process. Thus, except for having to interrogate the underwater transponders, the positioning and aligning operation is the same as that previously considered in the FIG. 4 case.

After the drill bit positioning device 60 has reached the bottom of the well bore 16, such device 60 is removed, as before, by increasing the fluid pressure within the drill string 30. As the nose portion of the closure member 61 breaks away from the drill bit 31, it pulls the plug 65 out of the source unit 63 and pulls both the plug 65 and the leads 64 out of the drill bit 31 so as to leave the passageway 33 and jet nozzle 34 clear for emitting the customary drilling jet. Following this, a wireline retrieving tool is lowered down the interior of the drill string 30 and hooked onto the hook member 69, whereafter the retrieving tool is returned to the drilling vessel 11 bringing with it the energy source unit 63. Thereafter, further drilling of the well bore 16 may be resumed.

Referring now to FIG. 6, there is shown a further embodiment of the invention which is particularly adapted for use with diamond drill bits. A diamond drill bit is generally indicated at 71 and includes a diamond studded cutting surface 72 which is formed on the bottom of the bit 71 and extends a short distance up the sides thereof. Bit 71 further includes an enlarged longitudinal center passage 73 adapted to receive a core barrel for purposes of taking a core sample of the subbottom earth formation. Bit 71 further includes an internally threaded portion 74 at the upper end thereof for purposes threaded portion 74 at the upper end thereof for purposes of connecting the bit 71 to the lower end of a string of drill pipe such as represented, for example, by the pipe string 12 in FIG.

1. Bit 71 further includes a plurality of vertically extending fluid conduits 75 for enabling emission of fluid from bottom located fluid outlet ports 76 during the drilling operation.

Secured to the bit 71 is a positioning and protecting device 80 having a protective closure member 81 which is fitted over and encloses the cutting portion of the bit 71. The nose portion of the closure member 81 extends below the lower end of the bit 71 and includes within the interior thereof a receptacle 82 for receiving a wireline signal radiating device of a type adapted to descend within the interior of the pipe string assembly to which the bit 71 is attached. The closure member 81 further includes a fluid passage system 83 formed within the body thereof for purposes of emitting a fluid jet from a side port 830 for producing the desired lateral thrust at the appropriate times. This fluid passage system 83 further includes longitudinally extending cavities 83b located adjacent the cutting surface 72 of the bit 71 and fluidly connected to a manifold ring 830 bv fluid conduits 83d. A further fluid conduit 83e extends laterally from the manifold ring 830 to the outlet port 83a. Cavities 83b are located so as to be in fluid communication with the outlet ports 76 on the bottom of the bit 71.

Shown positioned in the receptacle 82 of the closure member 81 and the passage 73 of the bit 71 is a wireline signal radiating instrument 84, which instrument 84 is suspended from the lower end of a wireline cable 85 which extends upwardly through the string of drill pipe to the drilling vessel 11. Cable 85 includes within the interior thereof appropriate insulated conductor wires for energy-curving and signal-carrying purposes. The signal radiating instrument 84 includes a lower sonde unit 84a which is located below the bit 71 and an upper electronic cartridge unit 84b which includes the electrical circuits for operating a transducer in the sonde unit 84a and for processing the signals received therefrom. The transducer in the sonde unit 84a takes the form of a scanning type transducer for emitting a rotating beam of signal energy and for detecting the signal energy reflected back from surrounding objects. As such, the sonde unit 84a functions in much the same manner as an electronic radar scanner except that, preferably, sound waves instead of electromagnetic waves are used to form the radiated beam. The scanning beam produced by the sonde unit 84a rotates around a vertical axis so as to produce a 360 lateral scanning of the environment surrounding the sonde unit 84a.

In use, the bit 71 including the positioning and protecting device is attached to the lower end of the drill string and is lowered to within a few feet above the top of the funnel device 14. The scanning instrument 84 is then lowered into the receptacle 82 of the closure member 81 and operating power is supplied thereto by way of cable to cause the radar type scanning of the surrounding environment. The radar type reflection signals from surrounding objects such as, for example, the funnel device 14, are detected by the transducer in sonde unit 84a and are processed by the circuits in the cartridge unit 84b to provide electrical signals which are sent up the cable 85 to a cathode-ray displav device located on the deck of the drilling vessel 11. Such signals produce a radar plan position ty e displav on the displav device and thus give the drilling operator a visual picture of the location of adjacent objects and, hence, of the position of the bit 71 and device 80 with respect thereto. The bit 71 is then brought into alignment with the mouth of the well bore 16 in the manner previously considered and then lowered into the well bore 16.

After the bit 71 has been lowered into the well bore 16, the scanning instrument 84 is withdrawn from the positioning and protecting device 80 and returned to the drilling vessel 11. A core barrel is then pumped down the drill string and seated in the passage 73 in the bit 71. Thereafter, the fluid pressure within the drill string is increased to remove the positioning and protecting device 80. Thereafter, the drilling and coring operations may be carried out in the customary manner.

Note that in the FIG. 6 embodiment it is not necessary to use any additional sounding buoys or sonic pulse transmitters or transponders for purposes of providing a fixed reference point. The position locating process is performed entirely by the wireline scanning instrument 84 which is lowered into the positioning and protecting device 80 during the appropriate phase of the operation.

From the foregoing descriptions of the various embodiments hereinabove described, it is seen that the present invention provides methods and techniques for producing a controllable lateral thrusting action on the lower end of a long string of underwater pipe, for protecting drill bits and other devices attached to the lower end of such long string of pipe and for providing an indication at the surface of the water of the location of the lower end of such long string of pipe. Such methods and techniques may be used in connection with a wide variety of devices which may be attached to the lower end of a long string of pipe. Such devices include various types of drill bits and cutting bits such as, for example, roller cone drill bits, diamond drill bits, core bits, drag bits, etc.

While there have been described what are at present considered to be preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, intended to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

l. A positioning and protecting device for enabling a pipe string assembly to be lowered to a desired underwater location comprising:

a. protective closure means for closing and protecting the lower end of the pipe string assembly; fluid passage means in said closure means with one end of the fluid passage means communicating with the interior of the pipe string assembly and the other end of the passage means arranged in said closure means laterally of the longitudinal axis of the pipe string assembly for emitting fluid laterally of the pipe string assembly for causing lateral movement thereof; and

c. fluid pressure responsive means within said closure means between said one end and said other end of said fluid passage means whereby fluid pressure within the pipe string assembly and acting on said fluid pressure responsive means may be employed to aid in removing said protective closure means.

2. A positioning and protecting device in accordance with claim 1 wherein the fluid pressure responsive means includes laterally extending cavity means formed within the body of the closure means, and the pressure means includes first fluid conduit means formed within the body of the closure means and extending from the cavity means to the interior of the pipe string assembly and second fluid conduit means formed within the body of the closure means and extending from the cavity means to the exterior surface of the closure means on one side thereof, such side being located laterally of the longitudinal axis of the pipe string assembly.

3. A positioning and protecting device in accordance with claim 1 wherein the pipe string assembly comprises a string of drill pipe having a cutting bit mounted on the lower end thereof, the closure means is fitted over and encloses the cutting portion of the bit and the fluid passage means communicates with at least one fluid passageway within the bit.

4. A positioning and protecting device in accordance with claim 3 wherein the cutting bit is a roller cone type drill bit and the closure means is fitted over and encloses the roller cone portion of the bit.

5. A positioning and protecting device in accordance with claim 3 wherein the cutting bit is a diamond drill bit and the closure means is fitted over and encloses the diamond studded cutting surfaces.

6. A positioning and protecting device in accordance with claim 3 wherein the cutting bit is a core bit and the closure means is fitted over and encloses the cutting surfaces thereof.

7. A positioning and protecting device in accordance with claim 1 wherein there is carried within and protected by the closure means a signal radiating means for ascertaining the location of the lower end of the pipe string assembly relative to the desired underwater location.

8. A positioning and protecting device in accordance with claim 7 wherein the closure means extends below the lower end of the pipe string assembly and the signal radiating portion of the signal radiating means is located therein at a point below the lower end of the pipe string assembly.

9. A positioning and protecting device in accordance with claim 8 wherein the pipe string assembly comprises a string of drill pipe having a cutting bit mounted on the lower end thereof, the closure means is fitted over and encloses the cutting portion of the bit, the fluid passage means carried by the closure means communicates with at least one fluid passageway within the bit and the signal radiating portion of the signal radiating means is located within the closure means at a point below the lower end of the bit.

10. A positioning and protecting device in accordance with claim 9 wherein the signal radiating means comprises transponder means for receiving an interrogation signal and emitting a reply signal in response thereto.

11. A positioning and protecting device in accordance with claim 9 wherein the signal radiating means comprises scanning means for emitting a rotating beam of signal energy and detecting the signal energy reflected from surrounding objects.

12. A positioning and protecting device in accordance with claim 1 wherein the closure means extends below the lower end of the pipe string assembly and the portion below such lower end includes an interior receptacle for receiving a signal radiating device of a type adapted to descend within the interior of the pipe string assembly.

13. A positioning and protecting device in accordance with claim 1 wherein the pipe string assembly comprises a string of drill pipe having a cutting bit mounted on the lower end thereof, the closure means is fitted over and encloses the cutting portion of the bit and extends below the lower end of the bit and a signal radiating means is carried within and protected by the closure means with the signal radiating portion thereof being located at a point below the lower end of the bit, and wherein the fluid passage means carried by the closure means includes laterallv extending cavity means formed within the body of the closure means immediately adjacent the cutting portion of the bit, a circular manifold passage located below the bit and encircling the signal radiating means, first fluid conduit means formed within the body of the closure means and extending from the cavity means to at least one fluid passageway within the bit, second fluid conduit means formed within the body of the closure means and extending from the cavity means to the circular manifold passage and third fluid conduit means formed within the body of the closure means and extending from the circular manifold passage to the exterior surface of the closure means on one side thereof, such side being located laterally of the longitudinal axis of the pipe string assemblv, and wherein the closure means is formed of a granular cementitious material whereby the portion thereof below the lower end of the bit may be removed from the bit by increasing the fluid pressure within the pipe string assembly.

PO-iOfiO LWYEE STA PATENT I QFFECE gel m r r mmmmw 0F CQREQTWN Patent No. 3,564,442 I j Dat d Mav 22. 1977 Inv n' fls) EUGENE R. ,ROSYSER and HOW ARD I LORENZ I It is certified that error appears in the abo e-identified pstent a-xd tha'a said Lefcpers Patent are hereby corrected as shown below:

Column 2, line 70, after "shpwing" insert a- Column 7, llne 4, cance lthe first "the" and substitute -to-.

Column 11, line 56, cencelgin its entirety. b

Signed and sealed this 5th day of SepQe-mber 1972.

(SEAL) Attest:

EDWARD M.FLET.CHER,JR.' ROBERT GOTTSCHALK Attesting Officer I Commissioner of Patents 

1. A positioning and protecting device for enabling a pipe string assembly to be lowered to a desired underwater location comprising: a. protective closure means for closing and protecting the lower end of the pipe string assembly; b. fluid passage means in said closure means with one end of the fluid passage means communicating with the interior of the pipe string assembly and the other end of the passage means arranged in said closure means laterally of the longitudinal axis of the pipe string assembly for emitting fluid laterally of the pipe string assembly for causing lateral movement thereof; and c. fluid pressure responsive means within said closure means between said one end and said other end of said fluid passage means whereby fluid pressure within the pipe string assembly and acting on said fluid pressure responsive means may be employed to aid in removing said protective closure means.
 2. A positioning and protecting device in accordance with claim 1 wherein the fluid pressure responsive means includes laterally extending cavity means formed within the body of the closure means, and the pressure means includes first fluid conduit means formed within the body of the closure means and extending from the cavity means to the interior of the pipe string assembly and second fluid conduit means formed within the body of the closure means and extending from the cavity means to the exterior surface of the closure means on one side thereof, such side being located laterally of the longitudinal axis of the pipe string assembly.
 3. A positioning and protecting device in accordance with claim 1 wherein the pipe string assembly comprises a string of drill pipe having a cutting bit mounted on tHe lower end thereof, the closure means is fitted over and encloses the cutting portion of the bit and the fluid passage means communicates with at least one fluid passageway within the bit.
 4. A positioning and protecting device in accordance with claim 3 wherein the cutting bit is a roller cone type drill bit and the closure means is fitted over and encloses the roller cone portion of the bit.
 5. A positioning and protecting device in accordance with claim 3 wherein the cutting bit is a diamond drill bit and the closure means is fitted over and encloses the diamond studded cutting surfaces.
 6. A positioning and protecting device in accordance with claim 3 wherein the cutting bit is a core bit and the closure means is fitted over and encloses the cutting surfaces thereof.
 7. A positioning and protecting device in accordance with claim 1 wherein there is carried within and protected by the closure means a signal radiating means for ascertaining the location of the lower end of the pipe string assembly relative to the desired underwater location.
 8. A positioning and protecting device in accordance with claim 7 wherein the closure means extends below the lower end of the pipe string assembly and the signal radiating portion of the signal radiating means is located therein at a point below the lower end of the pipe string assembly.
 9. A positioning and protecting device in accordance with claim 8 wherein the pipe string assembly comprises a string of drill pipe having a cutting bit mounted on the lower end thereof, the closure means is fitted over and encloses the cutting portion of the bit, the fluid passage means carried by the closure means communicates with at least one fluid passageway within the bit and the signal radiating portion of the signal radiating means is located within the closure means at a point below the lower end of the bit.
 10. A positioning and protecting device in accordance with claim 9 wherein the signal radiating means comprises transponder means for receiving an interrogation signal and emitting a reply signal in response thereto.
 11. A positioning and protecting device in accordance with claim 9 wherein the signal radiating means comprises scanning means for emitting a rotating beam of signal energy and detecting the signal energy reflected from surrounding objects.
 12. A positioning and protecting device in accordance with claim 1 wherein the closure means extends below the lower end of the pipe string assembly and the portion below such lower end includes an interior receptacle for receiving a signal radiating device of a type adapted to descend within the interior of the pipe string assembly.
 13. A positioning and protecting device in accordance with claim 1 wherein the pipe string assembly comprises a string of drill pipe having a cutting bit mounted on the lower end thereof, the closure means is fitted over and encloses the cutting portion of the bit and extends below the lower end of the bit and a signal radiating means is carried within and protected by the closure means with the signal radiating portion thereof being located at a point below the lower end of the bit, and wherein the fluid passage means carried by the closure means includes laterally extending cavity means formed within the body of the closure means immediately adjacent the cutting portion of the bit, a circular manifold passage located below the bit and encircling the signal radiating means, first fluid conduit means formed within the body of the closure means and extending from the cavity means to at least one fluid passageway within the bit, second fluid conduit means formed within the body of the closure means and extending from the cavity means to the circular manifold passage and third fluid conduit means formed within the body of the closure means and extending from the circular manifold passage to the exterior surface of the closure means on one side thereof, such side being located laterally of the longitudinal axis of the pipe string assembly, and wherein the closure means is formed of a granular cementitious material whereby the portion thereof below the lower end of the bit may be removed from the bit by increasing the fluid pressure within the pipe string assembly. 